Prostate cancer has become the most common cancer among American men. African American men have the highest incidence of any group in the world. Although generally a disease of men over the age of 65, prostate cancer is expected to be responsible for 32,000 deaths in 1991. Yet enthusiasm for early detection has been dampened by the large pool of "latent" cancers which can be found in the prostate of men who die of other causes. Despite the availability of transrectal ultrasonography (TRU) and the serum marker, prostate specific antigen (PSA), physicians hesitate to apply these tests in early detection because they are not confident that the cancers detected would be "clinically important, that is, a threat to the life or well-being of the host Careful studies to characterize the accuracy of ultrasonography in detecting prostate cancer, the pathologic features of detectable versus undetectable cancers, and to determine the ability of sonography to stage the disease, are urgently needed. Baylor College of Medicine seeks to continue to participate in the collaborative studies of the Ultrasound Prostate Cancer Network, along with the other members, to document the capability of ultrasonography to detect and stage prostate cancer, and to compare the ability of ultrasonography with that of digital rectal examination in serum PSA levels. Studies will be done within three clinical protocols: 101: Determination of the Ultrasonographic Characteristics of Adenocarcinoma of the Prostate and the Accuracy of Ultrasonography Compared to Digital Rectal Examination in Staging Apparently Localized Carcinoma of the Prostate; 102: Transrectal Ultrasonography of the Prostate Prior to Transurethral Resection for Presumed Benign Prostatic Hypertrophy; 103: Transrectal Prostate Ultrasonography Prior to Cystoprostatectomy for Treatment of Carcinoma of the Bladder. Ultrasonography will be performed using standardized techniques at each institution, and the interpretation will be recorded in a digitized format by the sonographer, a "blind reviewer" of the static films, and an "informed reviewer" of the films given the essential clinical details. Using receiver operating characteristic curve analysis and the pathologic finding as a "gold standard," these studies will determine the accuracy of sonography for detecting and staging prostate cancer. These studies will allow us to describe the pathologic features that determine the threshold of detectability of the presence and extent of cancer with ultrasonography. This information, gleaned principally from protocol 101, will be used in protocol 103 to assess the accuracy of ultrasongraphy in a population of patients without a clinical diagnosis of prostate cancer but whose prostates will be available for pathologic examination, to establish the presence or absence of prostate and the pathologic features of any cancer present. This population will simulate candidates for screening in the general population and will help to establish the appropriate role of sonography in the early detection of prostate cancer.